In recent years, a method is proposed in which a digital data file, for example, an audio visual (AV) data file, is transferred to a mobile terminal to be played back in the mobile terminal (e.g., refer to Patent Document 1).
Further, even if the digital AV data is data compressed using MPEG4-AVC or the like, its size is several ten to several hundred times as large as that of the audio data, and therefore it takes a long time to transfer the digital AV data to a mobile terminal. Furthermore, when the digital AV data stored in a recorder is transferred to a plurality of mobile terminals, transfer time corresponding to the number of mobile terminals is necessary.
For this reason, a method is proposed in which a one-to-multi transfer is performed using a multicast protocol as a method of efficiently transferring digital AV data stored in a recorder to a plurality of mobile terminals (e.g., refer to Patent Document 2).
Patent Document 1 is Japanese Patent Application Kokai Publication No. 2006-4543 (page 1, FIG. 3).
Patent Document 2 is Japanese Patent Application Kokai Publication No. 2003-223384 (page 1, FIG. 1).